Several industries utilize conveyor belts for transporting loads from one location to another location or for passing loads through successive processing operations. Many of these applications require conveyor belts that are able to maintain cleanliness under various and sometimes harsh conditions. For example, in the food and dairy industries, conveyor belts must provide sanitary surfaces for conveying food and dairy products to minimize the potential for contaminating these products. To meet this need, conveyor belt surfaces are often formed of materials, for example thermoplastic materials, that do not become easily contaminated when contacted with food or dairy products on the conveyor belt surface. To provide additional stability, light to medium duty conveyor belts used in these applications are typically formed in a plurality of plies, including one or more fabric layers sandwiched between thermoplastic or rubber layers. Thus, in the food product industry, for example, the conveying surface may be formed of a thermoplastic material that does not easily absorb liquid from conveyed food, while the carcass may be formed from a woven fabric to provide strength to the conveyor belt. In addition, in the food product industry and other industries, belts with uniform thicknesses and smooth continuous surfaces have greater strength, produce less wear on a conveyor system, and operate using smaller rollers than belts with non-uniform thicknesses or non-continuous surfaces.
During installation and maintenance of conveyor belts, the ends of one or more conveyor belts often must be joined together. While several existing methods and tools are capable of joining belt ends together, such as using adhesive or mechanical fasteners to adjoin the belt ends, welding is often the preferred method of joining the ends of conveyor belts, including light to medium duty polyvinyl chloride (PVC), polyurethane, and polyester belts, because it generally provides a more uniform and continuous joint and surface than other methods.
Welding ends of a conveyor belt together typically includes preparing the ends of the belt for splicing in a generally overlapping or intermeshing pattern, positioning the prepared belt ends together in a generally end-to-end orientation between a pair of heated plates, and subjecting the belt ends to specific temperatures and pressures applied by one or both of the plates for a specific amount of time to cause the material in the belt ends to melt or soften and flow together. Upon subsequently cooling the belt ends and releasing the pressure therefrom, the material will re-harden, fusing the material of the two belt ends to join the belt ends together. However, prior splice presses may have several deficiencies that limit usage of the splice presses.
Firstly, some prior splice presses are electrically inefficient. For example, some prior splice presses have thick metal platens, e.g., 20 mm thick, and a substantially rigid insulating member of heat insulating material between the platens of the splice press and the belt ends. This substantially rigid member may provide a more desirable heat distribution across the belt ends including a center hot zone and laterally outer cool zones.
Thick platens and an insulating member, however, increase the amount of mass that must be heated within the system because the entire thickness of the platens and the insulating member must be heated. Because more heat must be provided in order to sufficiently heat the belt ends, this additional heat must also be removed by the system prior to performing a subsequent splice, increasing the cycle time of the press for each belt splicing operation. Further, in some environments only relatively low voltage outlets, e.g., 110V, is available. There may simply not be sufficient power available to fully heat these prior splice presses because of the energy consumed in heating the thick platens and insulating member.
Another disadvantage of thick platens and a substantially rigid insulating member of prior splice presses is that they may increase the time required for heating the belt engaging surfaces of the splice press and for removing heat after the splice is formed. This delay decreases the ability of the user to quickly apply and remove heat from the belt ends. As a result, the quality of the splice may suffer because the quality of the splice depends on the temperature of the heated surfaces applied to the belt ends and the amount of time the belt ends are exposed to the temperature. For example, conveyor belt ends heated for too long of a duration may cause may undesirable amounts of material flow and/or degradation of the belt material. For a thermoplastic material belt with a fabric layer, this undesirable material flow could include bleeding of the thermoplastic material through the fabric layer of the belt which can create an area of high friction for the belt. Thus, the ability to quickly cool down the surfaces of the splice press can affect the resulting quality of the splice.